Six modules take their secrets from files; the rest say precisely why not

From the survey of every env-file secret (ADR 0086, issue 041): amqp-ping,
minio, mongodb and grafana use the _FILE twin their software honours;
mesh-catalog and model-usage read DATABASE_URL_FILE (a file the mesh
templates, mounted where only the runtime reads it); grafana's secret files
belong to its own account. Two dead deliveries removed: a line nothing read
in amqp-email-forwarder, and mailu's secret.env on four containers that
never read it. The 25 exceptions that remain carry the surveyed reason —
convertible and awaiting a bed, convertible through a generated config file,
the application's own code, or not convertible.

modules/model-usage/module.json

@@ -39,11 +39,11 @@
       "mode": "0700"
     },
     {
-      "id": "db-env",
+      "id": "database-url",
       "type": "file",
-      "path": "/var/lib/model-usage/db.env",
+      "path": "/var/lib/model-usage/database.url",
       "mode": "0600",
-      "content": "DATABASE_URL=postgresql://${bound:postgres-database:as}:${secret:postgres-database}@${bound:postgres-database:at}:${bound:postgres-database:port}/${bound:postgres-database:as}\n"
+      "content": "postgresql://${bound:postgres-database:as}:${secret:postgres-database}@${bound:postgres-database:at}:${bound:postgres-database:port}/${bound:postgres-database:as}\n"
     },
     {
       "id": "runtime",
@@ -53,15 +53,16 @@
       "network": "host",
       "volumes": [
         "/var/lib/mesh/model-usage/broker:/run/secrets/broker:ro",
-        "/var/lib/model-usage:/run/state"
+        "/var/lib/model-usage:/run/state",
+        "/var/lib/model-usage/database.url:/run/secrets/database-url:ro"
       ],
       "env": {
-        "MESH_BROKER_FILE": "/run/secrets/broker"
+        "MESH_BROKER_FILE": "/run/secrets/broker",
+        "DATABASE_URL_FILE": "/run/secrets/database-url"
       },
       "env-file": [
         "/var/lib/model-usage/db.env"
-      ],
-      "secrets-in-environment": "the mesh's own runtime reads MESH_STORE_* from the environment; a file twin in the SDK is the per-module work of issue 041"
+      ]
     }
   ]
 }